I've had one for around 8 years now, but it has lost its charge. I will need to re-magnetize it at some point. Mine used to be sensitive as well but I haven't had an issue with that for several years. Smashing that finger though can be pretty rough! I've never heard of one of these magnets rejecting (I am assuming it is in a silicone sheath). I do currently have a transdermal horn that has been rejecting pretty hard for the past 5 years that I really need to do something about though.